(1) Field of the Invention
The present invention relates to a liquid crystal display device having a cooling mechanism.
(2) Description of Related Art
In recent years, as a display device, a luminous type plasma display panel or a non-luminous type liquid crystal display device have been frequently used in place of a cathode ray tube (CRT).
Among them, the liquid crystal display device employs a liquid crystal panel as a transmission type light modulation element, and is provided with a lighting device (also called as a back light) on a back surface of the liquid crystal panel so as to irradiate a light onto the liquid crystal panel. Further, the liquid crystal panel forms an image by controlling a transmission rate of the light irradiated from the back light.
One of the features of the liquid crystal display device exists in a point that an outer shape can be structured thinner than the CRT. However, a further thinner liquid crystal display device is desired in recent years. If the liquid crystal display device is made thinner, it becomes hard to secure an air flow path for cooling an inner portion of a casing constructing an outer shape of the liquid crystal device. Accordingly, there generated a problem that a cooling efficiency is lowered. In this connection, for example, patent document 1 (JP-A-2006-189850 (refer to FIGS. 5 to 7)) discloses a technique in which a transverse flow fan for exhausting is provided in an upper portion of a rear surface so as to forcibly generate a convection current in an inner portion of a casing and increase an amount of an air flowing in the inner portion of the casing, thereby cooling the inner portion of the casing.
However, in the technique disclosed in the patent document 1, it is necessary to set a rotating space for rotating the transverse flow fan around a shaft provided in a lateral direction of the liquid crystal display device, and a space for arranging a rotating mechanism rotating the transverse flow fan, and there is generated an obstructing factor against the desire for making the liquid crystal display device thin.
In this connection, there is considered a structure in which a blower device taking an air from a rear surface of the liquid crystal display device so as to exhaust the air to an upper side is installed near a lower end of the liquid crystal display device, for making the liquid crystal device thin. This structure is structured such as to cool the inner portion of the casing by using both a forced convection generated by the blower device and a natural convection generated in the inner portion of the casing, however, if the blower device is installed near the lower end of the liquid crystal display device, the natural convection is disturbed by the flow of the forced convection generated by the blower device, and there is a problem that a whole of the inner portion of the casing of the liquid crystal display device can not be efficiently cooled.